need help troubleshooting a pair of powered speakers for pc

Did you check with the scope to see if the filter caps are doing their work?

Take care about how much time and money you spend to service your speakers. These are generally not very expensive to replace. The parts can end up costing more than the speakers are worth.

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Jerry G. ======

Took apart, verified 9VDC was coming in, but was not dropping any voltage. Noticed a lot of the solder joints looked poor. So I touched up the solder connections on board.

Now, power is going through circuit, diode dropping .5 V, but front panel LED still not coming on, and speaker 'hums'. When off, can hear audio very weakly through speaker. (using a handheld radio for signal)

Since have an Oscope at work, followed wires to chip with power off, and audio signal is present at chip, a KA 2006.

When powered on, just get big sine wave on Oscope, and lose audio. No response from volume pot.

Desoldered the KA 2006 chip, will try to purchase locally, but am wondering is there anything I may have missed? No signs of burnt parts.

Any help is greatly appreciated.

Thank you.

Jay

No I didnt... But I am just using spare time at work to learn a little and consider it an educational expense.

I will check those caps, like you suggested.

Thank you.

Jay

Jerry G. wrote:

their work?

speakers.

up

audio

touched

hear

signal)

No

Not able to deteremine which caps are the filter caps. Checked caps near the power switch, none had.

The 'hum' on speaker is about 2 VppAC and 120 Hz. Printed the pin breakout for the KA 2206 chip. There is a RIPPLE FILTER inside of chip, from the VCC input. But the large 120 Hz is still present on output pins.

I know it seems silly to spending this much time on this. If anyone has any idea where I can view schematics for this type of inexpensive power supply, amplifier setup, would be greatly appreciated. Or just any troubleshooting advice to assist me.

Thank you.

Jay

Jay, Get a large cap, 1000uF at a suitable voltage and clip lead it across the DC power supply leads. Observe polarity. Then give it a try.

-- Tony Marsillo Nutmeg Repair

Thank you, will try this when get back to work on Thursday. Will let you know how it goes..

Jay